Synergistic heat stabilizer compositions containing an antimony or a bismuth compound

ABSTRACT

The combination of a conventional antimony-or bismuth-containing heat stabilizers with certain aromatic esters or aryloxides containing boron, phosphorus, silicon, antimony, tin or zinc interacts synergistically to provide an unexpectedly high level of heat stability to halogen-containing polymers such as polyvinyl chloride (PVC). In addition the aromatic ester or aryloxide inhibits spontaneous degradation of the heat stabilizing component in the presence of heat and/or light.

BACKGROUND OF THE INVENTION

This invention relates to heat stabilizers for polymers derived fromhalogen-containing ethylenically unsaturated compounds such as vinylchloride and vinylidene chloride. This invention further relates to heatstabilizers for halogen-containing polymers containing an antimony orbismuth compound and a second component which synergistically improvesthe level of heat stability imparted by the antimony or bismuthcompound.

The efficacy of certain compounds of antimony and bismuth as heatstabilizers for halogen-containing polymers such as polyvinyl chlorideis well known. For example, U.S. Pat. Nos. 2,680,726; 2,684,956;3,399,220; 3,466,261; 3,493,536; 2,161,024; 2,461,531; 2,556,420;2,556,208; 2,801,988 and 3,530,158 disclose various sulfur- andnon-sulfur-containing antimony compounds that are useful for thispurpose. While these antimony compounds do impart considerable heatstability to halogen-containing polymers they have a number ofdisadvantages, two of the more serious ones being the tendency of manyantimony compounds to exude from the polymer composition and theinherent instability of some sulfur-containing antimony compounds uponexposure to heat or light for relatively short periods of time.

In addition, antimony compounds are often more costly than otherconventional heat stabilizers and do not possess any advantages inperformance to balance their shortcomings. These disadvantages havedelayed the commercial acceptance of antimony compounds as heatstabilizers for halogen-containing polymers.

It has now been found that the long-term stability of certain antimonyand bismuth compounds and the efficacy of these compounds as heatstabilizers for halogen-containing polymers such as polyvinyl chloridecan be synergistically improved by the presence of aryloxides oraromatic esters containing boron, phosphorus, silicon, antimony, tin orzinc.

SUMMARY OF THE INVENTION

This invention provides improved compositions for imparting heatstability to polymers of ethylenically unsaturated hydrocarbons. Thecompositions comprise a heat stabilizer selected from the grouprepresented by the formulae MX₃, MX_(n) Y_(3-n), RM=S and R_(n) MX_(3-n)wherein M is antimony or bismuth, R is hydrocarbyl, n is 1 or 2 and Xand Y each represent the residue obtained by removing (1) the hydrogenatom from the carboxy (--COOH) group of a mono- or polyfunctionalcarboxylic acid or mercaptocarboxylic acid or (2) the hydrogen atom fromthe sulfur atom of a mercaptan, mercaptoalkanol, mercaptocarboxylic acidor an ester of a mercaptocarboxylic acid or mercaptoalkanol, and whereinthe improvement resides in the presence in said composition of acompound containing at least one residue obtained by removing one orboth hydrogens from the two hydroxyl groups of a o-dihydric phenol, saidresidue being bonded through oxygen to an element selected from thegroup consisting of boron, phosphorus, silicon, antimony, tin and zinc.

DETAILED DESCRIPTION OF THE INVENTION

The aromatic ester or aryloxide compound disclosed in the preceedingSummary of the Invention and defined in greater detail hereinaftereffectively retards decomposition of the inherently unstable antimony-or bismuth-containing heat stabilizer in the presence of moisture, heatand/or light in addition to synergistically improving the performance ofthe heat stabilizer.

The heat stabilizing component of the present compositions can berepresented by one of the three foregoing generic formula.Alternatively, this component can be represented by one of the followingseven formulae, which indicate in greater detail the varioushydrocarbyl, sulfur- and oxygen-containing groups that can be bonded tothe antimony or bismuth atom. ##STR1##

In the foregoing formulae I-VII M represents either antimony or bismuth,antimony compounds being preferred. A is oxygen or sulfur and Rrepresents a hydrocarbyl group.

As used in this specification the term "hydrocarbyl" includes alkyl,cycloalkyl, aryl, alkaryl or aralkyl. The alkyl portion of anyhydrocarbyl group contains from 1 to 20 carbon atoms. The hydrocarbylgroup may contain one or more substituents, such as hydroxyl. In thisinstance the group "--SR" in the foregoing formula I could represent theresidue of a mercaptoalcohol remaining following removal of hydrogenfrom the mercapto (--SH) group, and R could be represented by ##STR2##wherein R₅, R₆, R₇, R₈, a and b are defined hereinafter.

Compounds corresponding to the formula M(SR)₃ are prepared by reacting amercaptan or mercaptoalcohol represented by the formula HSR with anantimony or bismuth trihalide in the presence of an acid acceptor orwith antimony or bismuth oxide. It has been previously disclosed thatthe residue remaining following removal of the mercapto (--SH) group ofsuitable mercaptoalcohols exhibits the general formula ##STR3## whereinR⁵ and R⁷ are individually selected from hydrogen, hydroxyl, halogen,mercapto, alkoxy, aryloxy and alkyl containing from 1 to 8 carbon atoms.The groups represented by R⁶ and R⁸ are hydrogen or alkyl containingfrom 1 to 18 carbon atoms. The terms a and b each represent an integerfrom 1 to 20, inclusive. The foregoing definitions are based on theproviso that the group R contains from 1 to 20 carbon atoms, aspreviously defined.

Compounds represented by the general formula II, M(SR¹ COOR²)₃, arederivatives of mercaptocarboxylic acid esters. In this formula R¹represents alkylene, arylene or aralkylene (e.g. xylyl) wherein anyalkylene or aralkylene group contains from 1 to 20 carbon atoms and R²represents a substituted or unsubstituted alkyl, aryl or aralkyl (e.g.benzyl) group. Typically R¹ represents the hydrocarbyl portion of amercaptoacetic, β-mercaptopropionic, thiomalic, thiosalicylic or othermercaptocarboxylic acid containing from 1 to 21 carbon atoms, and R²represents the hydrocarbyl or hydroxyhydrocarbyl portion of theesterifying alcohol, which contains from 1 to 20 carbon atoms andtypically can be methanol, n-propanol, iso-propanol, n-butanol, theisomeric octanols and decanols, glycerol, ethylene glycol,phenoxyethanol, pentaerythritol or trimethylol propane. Readilyavailable mercaptoacid esters that can be employed to prepare compoundscorresponding to the foregoing formula II include methylmercaptoacetate, amyl mercaptoacetate, isooctylmercaptoacetate,isodecylmercaptoacetate, dodecylmercaptoacetate,octadecylmercaptoacetate and in general the esters of mono and dibasicaliphatic and aromatic mercaptoacids, such as esters ofbeta-thiopropionic acid, thiolactic acid, thiobutyric acid andmercaptolauric acid.

In the foregoing formula III, which represents antimony or bismuthderivatives of mercaptoalkanol esters, R³ is alkylene, contains at least2 carbon atoms and exhibits the formula ##STR4## and Z represents theresidue obtained by removing the hydroxyl portion of a carboxy groupfrom a mono- or polycarboxylic acid. All of the "R" terms in thisformula have been previously defined. The group --SR³ OZ in formula IIIcan represent, for example, the residue obtained by removal of thehydrogen atom from the mercapto group of 2-mercaptoethyl caprylate,2-mercaptoethyl isooctyl maleate, 3-mercaptopropyl butyl azelate or1-thioglyceryl oleate.

Generic formula IV, R_(n) ¹¹ MX_(3-n), is representative oforganoantimony or organobismuth derivatives of mercaptides,mercaptoalkanol esters, mercaptoacid esters, carboxylic acids,thiocarboxylic acids, alcohols and phenols. R¹¹ represents alkyl,cycloalkyl, alkenyl, alkynyl, aryl, cycloalkenyl or aralkyl, each ofwhich may contain one or more substituents such as alkoxy, hydroxyl oramino groups. The alkyl portion of any group represented by R¹¹ containsfrom 1 to 20 carbon atoms. The term "X" represents one of theaforementioned anionic residues (mercaptide, mercaptoester, etc.) and isbonded to the metal atom through oxygen or sulfur. If X represents theresidue of a mercaptoacid ester, X can be further defined as --SR¹COOR². R¹ and R² have been previously defined in the discussion offormula II and n is 1 or 2.

Formula VII, R¹¹ M=S, represents the class of organoantimony- andorganobismuth sulfides exemplified by butylantimony sulfide.

When R¹¹ of formulae IV and VII represents alkyl, this definitionincludes, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl,i-butyl, n-amyl, n-octyl and 2-ethylhexyl in addition to substitutedalkyls such as phenylethyl and benzyl. Typical alkenyl groups includevinyl, 2-propenyl (i.e. allyl), 1-propenyl, 1-butenyl and 2-butenyl, inaddition to inertly substituted alkenyl groups exemplified by4-phenylbuten-1-yl. Typical cycloalkyl groups include cyclohexyl,cycloheptyl and cyclooctyl in addition to inertly substituted cycloalkylgroups such as 2-methyl cycloheptyl, 3-butyl cyclohexyl. Typical alkynylgroups include propyn-1-yl, propyn-2-yl, butyn-1-yl, phenylethynyl andethynyl. Typical aryl groups include phenyl, tolyl, xylyl, chlorophenyland dimethylaminophenyl. Where more than one R¹¹ or X is present informula IV, these can be identical or different. Typical mercaptideresidues represented by X include phenyl mercaptide, lauryl mercaptide,butyl mercaptide and dimercaptides wherein the hydrocarbon group isdivalent aliphatic, cycloaliphatic, or aromatic. Specific compounds whenn of formula IV is 1 or 2 include n-butyl antimony dilaurylmercaptide,di-n-butyl antimony lauryl mercaptide, diphenyl antimony laurylmercaptide, ditolyl antimony n-amyl mercaptide, dibenzyl antimony benzylmercaptide, diallyl antimony cyclohexyl mercaptide, diphenyl antimonyallylmercaptide, dicyclohexyl antimony n-hexyl mercaptide, ditolylantimony phenyl mercaptide, di-isopropyl antimony 2-ethylhexylmercaptide, di-p-chlorophenyl antimony n-butyl mercaptide anddiphenylantimony ethylmercaptoacetate. Patents disclosing such antimonycompounds include U.S. Pat. Nos. 3,530,158 and 3,399,220. When Xrepresents the residue of an alcohol or a monohydric phenol, typicalcompounds of this type include methanol, ethanol, 2-ethylhexanol,phenol, nonylphenol and the isomeric xylenols.

Compounds corresponding to the foregoing formula V, ##STR5## arederivatives of carboxylic, thiocarboxylic and dithiocarboxylic acids,depending upon the definition of A, which can be either oxygen orsulfur. R⁴ is a hydrocarbyl group as previously defined for the term"R".

The heat stabilizers encompassed by the present invention includecompounds containing two different classes of anionic groups bonded toantimony or bismuth. This class of compounds is represented by theforegoing generic formula VI, ##STR6## The definitions for A and R⁴ areas previously defined for formula V, R¹⁶ is hydrocarbyl as previouslydefined for R or R¹⁶ can represent --R¹ COOR² (viz. generic formula II)or --R³ OZ (viz. generic formula III). The subscript "g" represents theinteger 1 or 2.

In all of the foregoing formulae I-VI when one or more R, R¹, R², R³, Zor R⁴ groups are present on a molecule, these can be identical ordifferent. Methods for preparing all of these compounds and the utilityof these compounds as stabilizers for halogen-containing polymers arewell known in the art, for example from the disclosures of U.S. Pat.Nos. 2,680,726; 2,684,956; 3,399,220; 3,466,261; 3,493,536; 2,161,024;2,461,531; 2,556,420; 2,556,208; 2,801,988 and 3,530,158. The pertinentsections of the aforementioned patents are hereby incorporated byreference.

The following listing of specific antimony and bismuth compounds thatfall within the scope of the present invention with respect to the heatstabilizing component indicates the variety of compounds and is notintended to limit the scope of the accompanying claims.

Antimony trisdodecylmercaptide

Bismuth trisdodecylmercaptide

Antimony trisphenylmercaptide

Bismuth

Antimony trisbenzylmercaptide

Bismuth

Antimony tris(2-hydroxyethyl mercaptide)

Bismuth tris(3-mercaptopropyl mercaptide)

Antimony tris(methyl mercaptoproprionate)

Bismuth tris(butyl mercaptoacetate)

Antimony tris(isooctyl mercaptoacetate)

Bismuth tris(isodecyl mercaptopropionate)

Antimony tri(dodecyl mercaptopropionate)

Bismuth tris(octadecyl mercaptoacetate)

Antimony tris(benzyl mercaptoacetate)

Bismuth tris(allyl β-mercaptopropionate)

Antimony gris(octyl γ-mercaptobutyrate)

Bismuth tris(ethyl-γ-mercaptobutyrate)

Antimony tris(isopropyl δ-mercaptovalerate)

Bismuth tris(diamyl thiomalate)

Antimony tris(pentaerythrityl mercaptoacetate)

Bismuth tris(trimethylolpropane mercaptopropionate)

Antimony tris(thiobenzoate)

Bismuth tris(thiolaurate)

Antimony tris(caprylate)

Bismuth tris(stearate)

Antimony tris(oleate)

Bismuth tris(benzoate)

Antimony tris(methyl maleate)

Bismuth tris(butyl maleate)

Antimony tris(hexyl adipate)

Bismuth tris(octyl succinate)

Antimony tris(methyl azelate)

Bismuth tris(isooctyl fumarate)

Antimony tris(2-mercaptoethyl pelargonate)

Bismuth tris(2-mercaptoethyl caprylate)

Antimony tris(mercaptopropyl stearate)

Bismuth tris(1-thioglyceryl butyrate)

Antimony tris(2-mercaptopropyl butyl maleate)

Bismuth tris(2-mercaptopropyl methyl azelate)

Tetra[antimony]tris(pentaerythrityl tetramercapto acetate)

Antimony bis(dodecylmercaptide)stearate

Bismuth isooctyl mercaptoacetate bis(laurate)

n-butylantimony bis(dodecyl mercaptide)

Di-n-butylantimony dodecyl mercaptide

Diphenylbismuth dodecyl mercaptide

Diphenylantimony benzylmercaptide

Diallylantimony isooctylmercaptoacetate

Di-n-butylbismuth methylmercaptopropionate

Bis(antimony) tris(S,O-mercaptoacetate)

Bis(bismuth) tris(S,O-mercaptopropionate)

Antimony bis(dodecylmercaptoacetate)dodecylmercaptide

Bismuth bis(isooctylmercaptopropionate)cyclohexylmercaptide

Antimony methylmercaptopropionate dodecylmercaptide stearate

Another class of compounds that can be employed as the heat stabilizercomponent of the present compositions are the bimetallic compoundscontaining antimony and tin that are disclosed in the U.S. Pat. No.2,934,548; French Pat. No. 1,531,398; Japanese Pat. No. 72 06, 106.Representative compounds within this class include [mono(dibutyltinmonooleate)mono(antimony-mono-2-ethylhexoate-mono-2-ethylhexylmercaptoacetate)] sebacate and the compound represented by the formula##STR7##

The second component of the present stabilizer compositions actssynergistically with the previously described heat stabilizer to impartunexpectedly high levels of heat stability to halogen-containingpolymers such as polyvinyl chloride. The compounds constituting thesecond component are derivatives of diphenols wherein the two hydroxylgroups are located on adjacent carbon atoms of a phenyl or otheraromatic carbocyclic ring structure and can be represented by one of thefollowing three generic formulae. ##STR8##

In the foregoing formulae A, B and C R¹², R¹³, R¹⁴ and R¹⁵ can beidentical or different and are selected from the group consisting ofhydrogen, halogen, amine, nitro, nitroso, sulfonyl, hydroxymethylene(--CH₂ OH), alkyl containing from 1 to 10 carbon atoms and aryl.Alternatively R¹² and R¹³, R¹³ and R¹⁴ or R¹⁴ and R¹⁵ can be bondedtogether to form an aromatic or an alkyl-substituted aromatic ringstructure such as phenyl or tolyl. The term "E" represents antimony,boron, silicon, phosphorus, zinc or tin. The subscripts m, p and q eachrepresent integers from 0 to 2, with the proviso that the sum of m, pand q is 1 when E is antimony, boron or phosphorus; the sum of m, p andq is 2 when E is tin^(IV) or silicon and m, p and q are all zero when Eis tin^(II) or zinc. The subscripts r, s and t each represent an integerfrom 0-3 with the proviso that the sum of these integers is 0 when E iszinc; this sum is 1 when E is tin^(II) ; this sum is 2 when E isantimony, boron or phosphorus; and this sum is 3 when E is tin^(IV) orsilicon. The substituents on E, represented by R¹⁷, R¹⁸ and R¹⁹ in theforegoing formulae A, B and C can be halogen or hydroxide, regardless ofthe element represented by E. When E is boron these substituents canadditionally be selected from the group consisting of alkyl, aryl,alkaryl and aralkyl, wherein any alkyl group or alkyl portion of analkaryl or aralkyl group contains from 1 to 10 carbon atoms, R¹⁷, R¹⁸and R¹⁹ can also represent mono- and polyfunctional alkoxy, mono- andpolyfunctional aryloxy, --SR¹⁶, ##STR9## All of the terms in the threepreceding formulae have previously been defined. Alternatively, if thesum of m, p and q or the sum of r, s and t is 2 or more, any two of R¹⁷,R¹⁸ and R¹⁹ can collectively represent an oxygen atom.

When E is phosphorus, R¹⁷, R¹⁸ and R¹⁹ can additionally be selected fromalkoxide, aryloxide, siloxide [e.g., --OSi(CH₃)₃ ], ##STR10## or two ofR¹⁷, R¹⁸ and R¹⁹ can be combined to represent a doubly bonded oxygen orsulfur atom.

When E is silicon, R¹⁷, R¹⁸ and R¹⁹ can additionally be selected from--O--SiR²⁰ R²¹ R²², where R²⁰, R²¹ and R²² are alkyl, aryl, alkaryl oraralkyl wherein any alkyl group or alkyl portion of an alkaryl oraralkyl group contains from 1 to 10 carbon atoms, R²⁰, R²¹, R²²,##STR11## When E is antimony, R¹⁷, R¹⁸ and R¹⁹ can additionally beselected from R²⁰, --SR¹⁶, alkoxy, aryloxy, ##STR12##

When E is tin^(II), R¹⁷, R¹⁸ and R¹⁹ can additionally be selected fromthe residue obtained by removal of a hydrogen atom from a saturated orethylenically unsaturated, substituted or unsubstituted carboxylic acidof about 5 to 22 carbon atoms. When E is tin^(IV), R¹⁷, R¹⁸ and R¹⁹ canadditionally be selected from alkyl, aryl, alkaryl and aralkyl, whereinany alkyl group or alkyl portion of an alkaryl group contains from 1 to20 carbon atoms, --SR¹⁶, ##STR13##

Specific derivatives of o-diphenols that can be combined with antimonyor bismuth compounds to form the synergistic stabilizer compositions ofthis invention include, but are not limited to the following compounds:##STR14##

Ortho-substituted or ortho, ortho'-di-substituted aromatic ester oraryloxide compounds of boron, phosphorus, silicon, antimony, tin andzinc such as o-phenylene-orthosilicate, t-butyl-o-phenylene phosphite,o-phenylene-n-butyl-borate, 2,3-naphthalene borate anhydride,2-hydroxybenzodioxastibole, [tert-butyl 1,2-benzenediolato(2-)]tin (II),o-phenylene-dioxy-di-n-butylstannane, and the like are the presentlymost preferred compounds of this invention for use in combination withantimony compounds as synergistic PVC stabilizers. Except for some meta,meta'-di-substituted aromatic compounds, other aromatic ester oraryloxide compounds have not been presently found to provide synergisticthermal stabilization properties to polyvinylchloride.

For instance, based upon findings of synergisms and amounts ofcomponents where such synergisms might be found, most other seeminglychemically similar compounds do not display heat stabilizing synergismswith antimony organic sulfur and non-sulfur-containing compounds. Inunexpected contrast, however, ortho-substituted and ortho,ortho'-di-substituted ester and aryloxide compounds as hereinbeforedisclosed and the antimony or bismuth organic sulfur- andnon-sulfur-containing components in combination, provide highlyunexpected results. Such unexpected results along with other advantagesare empirically demonstrated in numerous operating examples of thisinvention, and a further understanding thereof will become apparent inview of the detailed description herein.

The following detailed examples will serve to illustrate the principlesof this invention in regard to its operating parameters, the types ofspecific materials which may be employed and their amounts used intypical poly(vinylchloride) resin formulations and particularly thesynergistic effects shown by the essential combination of components inthe stabilizer compositions according to this invention.

These examples are considered to be exemplary of this invention, andshould not be considered as limiting, especially in view of the broaddisclosure of principles of this invention.

The polyvinylchloride resin formulations used in the subsequent examplesare typical of those used in commercial applications. The variouscombinations of organic antimony sulfur or non-sulfur containingcompounds (Type I) and ortho-substituted or ortho, ortho'-disubstitutedaromatic esters or aryloxides (Type II) were either first blendedtogether to form storage-stable liquid or solid compositions and werethen mixed into the PVC formulations or the Type I and Type II compoundswere individually blended into the resin formulations according to thefollowing examples on a parts by weight basis. All amounts of suchstabilizer components, in the tables and examples, are on a parts (byweight) per hundred parts of resin basis, which is abbreviated as "phr."

The Type II compounds of this invention were incorporated in thestabilizer compositions on the basis of from 1 to 5 percent by weight ofthe antimony compound. However, up to about 10% or more can be used. Atthese usage levels liquid antimony and bismuth compounds of acceptablestability are formed. The presence of the Type II compounds imparts longterm stability to the antimony and bismuth compounds in addition toincreasing the efficacy of the antimony and bismuth compounds asstabilizers.

                  TABLE 1                                                         ______________________________________                                        FORMULATIONS     1       2       3     4                                      ______________________________________                                        Vinylchloride homo-                                                                            100.0   100.0   100.0 100.0                                  polymer (Diamond                                                              Shamrock PVC-450 or                                                           Tenneco 225-PG)                                                               Titanium dioxide --      1.0     1.0   1.0                                    Calcium carbonate coated                                                                       --      3.0     2.5   3.0                                    with stearic acid                                                             Calcium stearate --      0.5     0.6   0.5                                    Paraffin wax (XL-165 from                                                                      --      1.1     0.5   1.0                                    American Hoechst)                                                             Paraffin wax (XL-200 from                                                                      0.5     --      --    --                                     American Hoechst)                                                             Oxidized polyethylene wax                                                                      --      0.15    --    0.15                                   (AC-629A from Allied                                                          Chemical Corp.)                                                               Acrylic Processing Aid                                                                         2.0     --      --    --                                     (Acryloid K-120N from                                                         Rohm & Haas Co.)                                                              Stabilizer       as indicated                                                 ______________________________________                                    

The heat stability of the various formulations with and withoutadditives was evaluated by milling the formulation for five (5) minutesat 163° C. to form a homogeneous composition, removing the resultantproduct in the form of a coherent sheet and allowing it to harden bycooling it to ambient temperature on a flat surface. The sheets formedin this manner were cut into squares measuring 1×1 inch (2.5×2.5 cm.)and placed on trays. The trays were placed in a forced air oven at atemperature of 204° C. Test samples were removed from the oven atpre-selected time intervals. A record of heat stability, or colordevelopment with time, was obtained by assigning color ratings to eachsample. In this manner early color development and long-term heatstability properties for any stabilizer composition or componentsthereof are readily ascertained.

A second method for evaluating stabilizer compositions or individualcomponents thereof comprised forming compression molded plaques byplacing pieces of the aforementioned milled sheets side-by-side in ametal frame between highly polished chrome plated steel plates. Thiscomposite was then placed between the platens of a hydraulic pressmaintained at a temperature of about 177° C. and subjected to about18,000 kilograms ram pressure for about ten (10) minutes. The color ofthe resultant compression molded products was then rated either visuallyor by use of a colorimeter to measure Yellowness Index (Y.I.) values.These values were determined using a Meeco Colormaster TristimulusDifferential Colorimeter to measure the reflectance of green, red andblue light from the surface of the sample. The Y.I. value was thencalculated using the equation: ##EQU1##

EXAMPLES 1-8

The synergistic response of the combination of several ortho,ortho'-disubstituted aromatic ester compounds and antimonytris(isooctylmercaptoacetate) is clearly demonstrated in Examples 1-8.

In these examples the stabilizer combinations, as well as the individualcomponents thereof, were intimately blended into the resin formulationby milling them at 163° C. and oven tested for heat stability at 204° C.Table 2 summarizes the results.

The stabilizer components and combinations thereof employed in all ofthe examples in this specification are identified by numbers as follows:

    ______________________________________                                        Com-                                                                          ponent                                                                        Num-                                                                          ber   Identification                                                          ______________________________________                                        1     Antimony tris(isooctylmercaptoacetate)                                  2     No. 1, diluted to about 11% antimony with mineral oil                   3     Antimony tris(n-butylmercaptoacetate), diluted                                to about 11% antimony                                                   4     Antimony tris(pentaerythrityl-monocaprylate-                                  monomercaptoacetate)                                                    5     Antimony tris(2-hydroxyethylmercaptide), diluted                              to about 11% antimony with a non-reactive polar solvent                 6     Antimony trioleate                                                      7     4-t-butyl-o-phenylene pyroborate                                        8     No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 7.                                       9     Tris(o-phenylene) bis(phosphite)                                        10    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 9.                                       11    Tris(o-phenylene) bis borate                                            12    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 11                                       13    Bis(o-phenylene)orthosilicate                                           14    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 13                                       15    No. 1, diluted to about 11% antimony, and                                     containing 1% by weight of No. 9                                        16    No. 1, diluted to about 11% antimony, and                                     containing 1% by weight of No. 11                                       17    No. 1, diluted to about 11% antimony, and                                     containing 1% by weight of No. 13                                       18    o-Phenylene-n-butylborate                                               19    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 18                                       20    o-Phenylenepyroborate                                                   21    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 20                                       22    No. 4 containing 3% by weight of No. 18                                 23    A commercial, diluted antimony tris(issoctyl-                                 mercaptoacetate) product covered by U.S.                                      Patent 4,029,618                                                        24    2-Hydroxybenzodioxastibole                                              25    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 24                                       26    4-t-butyl-o-phenylenedioxydibutylstannane                               27    No. 1, diluted to about 11% antimony, and                                     containing 4% by weight of No. 26                                       28    Bismuth tris(isooctylmercaptoacetate), diluted                                to about 11% bismuth                                                    29    No. 28 containing 4% by weight of No. 18                                30    Bismuth tris(n-dodecylmercaptide), diluted                                    to about 11% bismuth                                                    31    No. 30 containing 4% by weight of No. 18                                32    Antimony tris(n-dodecylmercaptide), diluted                                   to about 11% antimony                                                   33    No. 32 containing 4% by weight of No. 9                                 34    Antimony tris(2-mercaptoethylcaprylate), diluted                              to about 11% antimony                                                   35    No. 34 containing 4% by weight of No. 13                                36    No. 6 containing 5% by weight of No. 18                                 37    No. 5 containing 4% by weight of No. 18                                 38    No. 3 containing 4% by weight of No. 18                                 ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        (Formulation 1).sup. b                                                        Com-                                                                          pon-           Color Development.sup.a with Time                              ent            (in minutes) at 204° C.                                 Num-               Ini-                                                       ber       PHR      tial   5    10   15   20  25                               ______________________________________                                        Ex. 1 No      --         4-   3+   3    2    1   1                                  add-                                                                          itive                                                                   Ex. 2 1       0.95       7-   6+   6-   5    2   1                            Ex. 3 18      0.05       4+   4    3    2    1   1                            Ex. 4 1       0.95                                                                                     7    7-   7-   6-   2   1                                  18      0.05                                                            Ex. 5 9       0.05       4+   4    3    2    1   1                            Ex. 6 1       0.95                                                                                     7    7-   6+   5    2   1                                  9       0.05                                                            Ex. 7 13      0.05       4    3+   3    2    1   1                            Ex. 8 1       0.95                                                                                     7    7    7-   6    4   1                                  13      0.05                                                            ______________________________________                                         .sup.a Color Scale: 7 =  clear, waterwhite 5 = light yellow 3 = orange to     redbrown 1 = very dark redbrown to black                                      .sup.b Refer to Table 1 for formulation                                  

Table 2 contains data which show that the use of 0.05 phr of each of thepresent Type II compounds in the absence of a Type I antimony or bismuthcompound does not significantly improve the inherently poor stability ofthe polyvinyl chloride resin. Antimony tris(isooctylmercaptoacetate)alone, however, at 0.95 phr was found to impart significant heatstability to the PVC Formulation. The fact that the Type II compoundseach at 0.05 phr when combined with antimonytris(isooctylmercaptoacetate) at 0.95 phr further improved both theshort- and long-term stability of the PVC resin demonstrates asynergistic response considering the poor stabilizing efficacy of theType II compounds.

EXAMPLES 9-18

The synergistic improvements demonstrated in Examples 1-8 arecorroboroated by the visual and colorimetric ratings for compressionmolded plaques prepared from the milled sheets of Examples 1-8. Thesheets were molded at 177° C. for ten (10) minutes. Examples 17 and 18additionally demonstrate the synergistic response for the combination ofbismuth tris(isooctylmercaptoacetate) and a typical Type II compound.

                  TABLE 3                                                         ______________________________________                                        (Formulation 1).sup.(a)                                                                            Color                                                                         Development on Compression                               Component            Molding 10 Minutes at 177° C.                     Number        PHR    Visual Rating                                                                            Yellowness Index                              ______________________________________                                        Example 9                                                                             no additive                                                                             --     2        188.1                                       Example 10                                                                            1         0.95   6        13.4                                        Example 11                                                                            18        0.05   3        155.3                                       Example 12                                                                            1         0.95   7        5.2                                                 18        0.05                                                        Example 13                                                                            9         0.05   3        133.0                                       Example 14                                                                            1         0.95   6+       11.7                                                9         0.05                                                        Example 15                                                                            13        0.05   2        184.5                                       Example 16                                                                            1         0.95   7        10.3                                                13        0.05                                                        Example 17                                                                            28        0.95   4-       79.3                                        Example 18                                                                            28        0.95   5-       43.1                                                18        0.05                                                        ______________________________________                                         .sup.(a) Refer to Table 1 for formulation                                

EXAMPLES 19-56

Table 4 exemplifies the synergistic improvement in heat stability bynumerous additional antimony and bismuth organic sulfur- andnon-sulfur-containing compounds in combination with aromatics esters andaryloxides typical of this invention.

In these examples the Type II compounds were blended with antimonytris(isooctylmercaptoacetate) prior to addition of the combination ofcomponents to the PVC formulations. Since the synergistists aregenerally used in relatively minor amounts, they are most preferablypre-blended with the antimony or bismuth compound rather than separatelyadded to the resin formulation. For instance, the stabilizer of Example29 is employed at a concentration of 0.35 phr, which consists of 0.3465phr of antimony compound and only 0.0035 phr of synergist. Optimumblending homogeneity is therefore best obtained by pre-blending thestabilizer components. Furthermore, the presence of the Type II compoundsignificantly improves the storage stability of the antimony or bismuthcompound. Thus, the pre-blended stabilizer compositions of thisinvention and the components thereof were intimately incorporated intothe resin formulations by two-roll milling for five (5) minutes at 163°C. The resultant PVC sheets were then compression molded into plaques totest them for heat stability as previously described. Examples 19-29clearly demonstrate the poor PVC stabilization efficacy of the Type IIsynergists alone. The visual and colorimetric ratings for each of thecombinations versus the ratings for antimonytris(isooctylmercaptoacetate) alone shows the superior performance ofthe combinations, even at very low synergist levels. These results arequite unexpected by virtue of the fact that the color ratings of theType II compounds alone are poorer than that of the antimony compoundalone. The Type II compounds would therefore not be expected tocontribute to the heat stability of the PVC resin composition.

Examples 30-40 show the diversity of synergistic Type II compounds ofthis invention which can be used in combination with antimony andbismuth compounds of Type I. The color values for these combinationsshow unexpected superiority over the individual components of thecombinations. In Examples 41-56 the heat stability imparted to PVC resinby a wide variety of antimony and bismuth sulfur- andnon-sulfur-containing compounds is shown to be synergistically improvedin much the same way as the compositions of Examples 19-29.

                  TABLE 4                                                         ______________________________________                                                               Color                                                  Component              Development on Compression                             Number                 Molding 10 minutes at 177° C.                   (Formulation           Visual                                                 2).sup.(a)     PHR     Rating.sup.(b)                                                                         Yellowness Index                              ______________________________________                                        Example 19                                                                            no additive                                                                              --      1      43.2                                        Example 20                                                                             2         0.35    5      22.7                                        Example 21                                                                            11         0.05    2+     37.1                                        Example 22                                                                            12         0.35    7-     15.4                                        Example 23                                                                            16         0.35    5+     20.2                                        Example 24                                                                             9         0.05    2      32.8                                        Example 25                                                                            10         0.35    6+     14.7                                        Example 26                                                                            15         0.35    5+     20.0                                        Example 27                                                                            13         0.05    2-     31.2                                        Example 28                                                                            14         0.35    7-     15.3                                        Example 29                                                                            17         0.35    5+     19.6                                        Example 30                                                                             2         0.4     5+     20.0                                        Example 31                                                                            18         0.05    3      38.8                                        Example 32                                                                            19         0.4     7      9.4                                         Example 33                                                                            20         0.05    3      47.9                                        Example 34                                                                            21         0.4     7      9.6                                         Example 35                                                                            24         0.05    4      35.0                                        Example 36                                                                            25         0.4     7      6.4                                         Example 37                                                                             7         0.05    3      45.0                                        Example 38                                                                             8         0.4     7      9.9                                         Example 39                                                                            26         0.05    3      43.0                                        Example 40                                                                            27         0.4     6      8.5                                         Example 41                                                                            28         0.4     5      16.6                                        Example 42                                                                            29         0.4     6      13.1                                        Example 43                                                                            32         0.4     3+     37.0                                        Example 44                                                                            33         0.4     5-     25.8                                        Example 45                                                                            34         0.4     5      16.1                                        Example 46                                                                            35         0.4     7-     9.3                                         Example 47                                                                             6         0.4     2      29.0                                        Example 48                                                                            36         0.4     4      19.9                                        Example 49                                                                             5         0.4     5+     19.0                                        Example 50                                                                            37         0.4     7      7.9                                         Example 51                                                                             3         0.4     6      19.7                                        Example 52                                                                            38         0.4     7      8.8                                         Example 53                                                                             4         0.5     5      20.4                                        Example 54                                                                            22         0.5     6      15.1                                        Example 55                                                                            30         0.4     2      33.7                                        Example 56                                                                            31         0.4     4      12.0                                        ______________________________________                                         .sup.(a) Refer to Table 1 for formulation                                     .sup.(b) Color Scale: 7 = White to Gray White                                   5 = YellowWhite to TanWhite                                                   3 = Tan to Gray                                                               1 = Dark Tan to dark Gray to dark                                            Grayish Pink                                                            

EXAMPLES 57-60

The data for examples 57-60, summarized in Table 5, demonstrate thesynergism achieved by combining antimony tris(isooctylmercaptoacetate)with Type II compounds over a wide range of antimony concentration (20milligrams to about 160 milligrams antimony metal per hundred grams ofpolyvinyl chloride resin). A synergistic response is achieved forcombinations of components beyond the range demonstrated in thefollowing table:

                  TABLE 5                                                         ______________________________________                                        (Formulation 4)                                                                                              Color Development                                                             on Compression                                                       Milli-   Molding 10 minutes                             Component             grams    at 177° C.                              Number       PHR      antimony Visual Rating.sup.b                                                                    Y.I.                                  ______________________________________                                        Example                                                                              1         0.95       158    6        7.0                               57                                                                            Example                                                                              1         0.95       155    7        6.3                               58                                                                                   18        0.05                                                         Example                                                                              2         0.2        21     4        21.4                              59                                                                            Example                                                                              19        0.2        20     6        14.2                              60                                                                            ______________________________________                                    

EXAMPLES 61-63

Table 6 provides further evidence for the synergistic stabilizationresponse exhibited by a combination of Type I and Type IIcompounds--which includes markedly improved early color and long-termstability, as determined by oven heat stability evaluation of a typicalPVC pipe compound.

                  TABLE 6                                                         ______________________________________                                        (Formulation 4)                                                               Com-              Color Development.sup.(b) with Time                         ponent            (in minutes) at 204° C.                              Num-              Ini-                                                        ber        PHR    tial   4   8    12   16   20   24                           ______________________________________                                        Ex-                                                                           ample 61                                                                              2      0.40   6    6   6-   5    2+   2    1                          Ex-                                                                           ample 62                                                                             18      0.05   4    3   3    3    2    2    1                          Ex-                                                                           ample 63                                                                             19      0.40   7    7   7    7-   2+   2+   2                          ______________________________________                                    

EXAMPLES 64-66

Improved shelf-stability of the liquid combination of components of thisinvention in comparison to an antimony compound alone is demonstratedusing data obtained by exposure of these materials, contained in flintglass vessels, to fluorescent light and incident sunlight upon standingon a laboratory bench over a period of time. The superiority of acombination of components of this invention over a commerciallyavailable antimony stabilizer composition of the closest prior art islikewise shown in Table 7. Additionally, Examples 64-66 clearly showimproved ultra-violet light stability of the liquid combination ofcomponents of this invention compared to an antimony compound alone andalso superior ultra-violet light stability of a product of thisinvention versus the closest prior art stabilizer. This latter evidencewas obtained by exposure of the example's components, contained in flintglass vessels, to Germicidal (RS) Sunlamps. The formation of solidprecipitates in Examples 64 and 66 and the lack of solids forming inExample 65 supports the additional principles of this invention.

                                      TABLE 7                                     __________________________________________________________________________                Exposure to Germi-                                                                          Exposure to fluores-                                Component   cidal (RS) Sunlamps                                                                         cent & Incident sunlight                            Number      Initial                                                                            1 Hr.                                                                              2 Hrs.                                                                            Initial                                                                             2 Weeks                                       __________________________________________________________________________    Example 64                                                                           2    Clear &                                                                            White &                                                                            Volu-                                                                             Clear &                                                                             Volumin-                                                  color-                                                                             brown                                                                              min-                                                                              color-                                                                              ous                                                       less ppt. ous less  white                                                               ppt.      ppt.                                          Example 65                                                                          19    Clear &                                                                            No   No  Clear &                                                                             Clear &                                                   color-                                                                             solids                                                                             solids                                                                            color-                                                                              color-                                                    less          less  less                                          Example 66                                                                          23    Clear &                                                                            Very Sl.                                                                           Sl. Clear &                                                                             Yellow                                                    color-                                                                             brown                                                                              brown                                                                             color-                                                                              with                                                      less ppt. ppt.                                                                              less  sl. brown                                                                     ppt.                                          __________________________________________________________________________

EXAMPLES 67-68

Other evidence of the superiority of compositions of this invention overthe closest prior art stabilizer comes from exposure of PVC formulationscontaining these stabilizers to Fluorescent Sunlamp-Black Light (FS-BL).For these examples, stabilizer components were two-roll milled intopolyvinylchloride resin formulations for five (5) minutes at 177° C. andfinally, exposure of the molded plaques in the FS-BL equipment. TheYellowness Index measurements of the plaques which were made initially,before exposure to the ultra-violet light source and following exposurefor 100 hours are listed in Table 8. In addition to the superiorultra-violet light protection that combinations of components of thisinvention provide to PVC formulations, in comparison to closest priorart stabilizers, superior early color properties are also demonstrated.

                  TABLE 8                                                         ______________________________________                                        (Formulation 3).sup.(a)                                                                             Yellowness Index with Time                              Component             (in hours) on FS-BL Exposure                            Number        PHR     Initial(O)   100                                        ______________________________________                                        Example 67                                                                            12        0.4     13.1       19.2                                     Example 68                                                                            23        0.4     19.3       22.7                                     ______________________________________                                         .sup.(a) Refer to Table 1 for formulations                               

EXAMPLES 69-70

Examples 69-70, shown in Table 9, demonstrate the superior resistance tocolor degradation on heating under pressure that a stabilizer mixture ofthis invention has compared to a closes prior-art stabilizer. Sheetsformed after two-roll milling PVC formulations containing theexemplified products for five (5) minutes at 163° C. were then convertedinto three (3) compression molded plaques by heating at 177° C. for 10,15 and 25 minutes, respectively. The Yellowness Index determined forthese moldings show the product of this invention to have superiorresistance to thermally induced color degradation.

                  TABLE 9                                                         ______________________________________                                        (Formulation 3)                                                                                    Color Development with                                                        Time (in minutes) on                                     Component            Compression Molding @ 177° C.                     Number        PHR    10       15      25                                      ______________________________________                                        Example 69                                                                            19        0.4    17.1   19.0    23.2                                  Example 70                                                                            23        0.4    20.9   22.0    26.5                                  ______________________________________                                    

EXAMPLES 71-73

The improvement in resistance to ultra-violet light induceddiscoloration for combinations of components of this invention over theantimony compound alone is shown by Examples 71-73 in Table 10. In thiscase, the exemplified components were intimately incorporated into a PVCformulation by two-roll milling into sheets. The sheets were thencompression molded for five (5) minutes at 177° C. into plaques and theplaques, in turn, were subjected to the effects of ultraviolet radiationin the FS-BL apparatus over an extended period of time. Yellowness Indexvalues were determined for each pressed sheet prior to U.V. exposure andperiodically after exposure. The superiority of products of thisinvention is clearly demonstrated.

                  TABLE 10                                                        ______________________________________                                        (Formulation 4)                                                                                    Yellowness Index                                                              with Time (in hours)                                                          on FS-BL Exposure                                        Number        PHR    Initial 100   200   300                                  ______________________________________                                        Example 71                                                                            2         0.4    11.2  16.0  22.1  30.1                               Example 72                                                                            12        0.4    7.1   13.5  20.2  28.5                               Example 73                                                                            19        0.4    8.0   13.8  19.7  26.8                               ______________________________________                                    

EXAMPLES 74-77

The following examples show the applicability of the compositions ofthis invention in providing extruded PVC pipe of superior color to thatmade with the antimony compound alone. As an added benefit, lowerextruder head pressures are found to result when this invention isemployed. Evaluation of several combinations of components of thisinvention in a typical PVC pipe formulation was accomplished by firstblending all the ingredients in a Henschel high-intensity mixer. Theresulting dry-blends were then extruded in a Modern Plastics MachineryCorporation Type 150-24LH extruder with a 11/2" (3.8 cm) screw, inconjunction with a 2.5 cm. pipe die. The data from these extrusions,listed in Table 11, in comparison to the results found for the antimonycompound alone are clearly demonstrative of the principles of thisinvention.

                  TABLE 11                                                        ______________________________________                                        (Formulation 2)                                                               Component           Pipe Color                                                                              Extruder Head                                   Number       PHR    Rating.sup.(b)                                                                          Pressure                                        ______________________________________                                        Example                                                                               2        0.4     6-     2100-2200 psi (1.47 ×                   74                              10.sup.5 -1.55 × 10.sup.5                                               g/cm.sup.2)                                   Example                                                                              12        0.4    7       1600-1700 psi (1.12 ×                   75                              10.sup.5 -1.2 × 10.sup.5                                                g/cm.sup.2)                                   Example                                                                              19        0.4    7       1500 psi (1.05 × 10.sup.5               76                              g/cm.sup.2)                                   Example                                                                              14        0.4    7       1100 psi (0.77 × 10.sup.5               77                              g/cm.sup.2)                                   ______________________________________                                    

EXAMPLES 78-80

Similar synergistic heat and light stabilizing principles of thisinvention can be demonstrated when antimonytris(n-dodecylmercaptoacetate), antimonybis(isooctylmercaptoacetate)mono-n-dodecylmercaptide, or bis(antimony)tris (glycoldimercaptopropionate) are substituted for the antimony orbismuth organic sulfur-or non-sulfur-containing compounds of thepreceding examples and similar procedures employed.

While the halogenated hydrocarbon resins which were employed in theabove examples were vinyl chloride homopolymers, it is to be understoodthat the scope of this invention is not to be limited to a particularvinly halide polymer such as polyvinyl chloride. Many other halogenatedhydrocarbon resins can be used to illustrate the principles of thisinvention. Specific examples include polyvinylidene chloride,chlorinated polyvinylchloride, polyvinylbromide, polyvinyl fluoride,chlorinated polyethylene and co-polymer resins predominatly containingpolymerized vinyl chloride along with smaller amounts of otherco-polymerized monomers such as ethlene, propylene, butylene, vinylacetate, vinyl ethers, vinyl alcohol, vinylidene chloride, styrene,acrylate esters, and the like.

Halogenated resin compositions other than the aforementionedFormulations 1-4 can be used to illustrate the principles of thisinvention. It is, therefore, also to be understood that a large varietyof other resin additives such as plasticizers, fillers, lubricants,impact modifiers, processing aids, pigments, colorants, flameretardants, other stabilizers, etc., may be incorporated in the polymerformulations to derive the benefits of the stabilizer compositions ofthis invention.

What is claimed is:
 1. In an improved composition for imparting heatstability to halogen-containing polymers of ethylenically unsaturatedhydrocarbons wherein the heat stabilizer exhibits the general formulaMX₃, MX_(n) Y_(3-n), RM=S and R_(n) MX_(3-n) wherein M is antimony orbismuth, R is hydrocarbyl, n is 1 or 2 and X and Y individuallyrepresent the residue obtained by removing (1) the hydrogen atom from acarboxy (--COOH) group of a mono- or polyfunctional carboxylic acid ormercaptocarboxylic acid or (2) the hydrogen atom from the sulfur atom ofa mercaptan, mercaptoalkanol, mercaptocarboxylic acid or an ester of amercaptocarboxylic acid or mercaptoalkanol, the improvement whichresides in the presence in said composition of a synergist containing atleast one residue obtained by removing one or both hydrogens from thehydroxyl groups of a o-dihydric phenol, said residue being bondedthrough one or both oxygen atoms to an element selected from the groupconsisting of boron, phosphorus, silicon, antimony, tin and zinc.
 2. Animproved composition according to claim 1 wherein said heat stabilizerexhibits a formula selected from the group consisting of M(SR)₃, M(SR¹COOR²)₃, M(SR³ OZ)₃, R_(n) ¹¹ MX_(3-n), ##STR15## and R¹¹ M=S, wherein Rrepresents hydrocarbyl or hydroxyalkyl, each of which contains from 1 to20 carbon atoms, R¹ is alkylene, arylene or aralkylene wherein anyalkylene group or alkylene portion of an aralkylene group contains from1 to 20 carbon atoms, R² represents substituted or unsubstituted alkyl,aryl or aralkyl, R³ is ##STR16## wherein R⁵ and R⁷ are hydrogen,hydroxyl, halogen, --SH, --OR', --OAr or R' wherein R' is alkylcontaining from 1 to 20 carbon atoms, Ar is aryl, R⁶ and R⁸ areindividually selected from hydrogen and alkyl containing from 1 to 8carbon atoms, R¹¹ is alkyl, cycloalkyl, alkenyl, alkynyl, aryl,cycloalkenyl or aralkyl, with the proviso that any alkyl group or alkylportion of an aralkyl group contains from 1 to 20 carbon atoms and anyalkenyl or alkynyl group contains from 2 to 20 carbon atoms, a and beach represent an integer from 1 to 20, A is oxygen or sulfur, g and nare 1 or 2, M is antimony or bismuth, Z represents the residue obtainedby removal of a hydrogen from the carboxyl group of a mono- ordicarboxylic acid containing from 2 to 20 carbon atoms or a half esterof said dicarboxylic acid, R⁴ is a hydrocarbyl selected from the samegroup as R, R¹⁶ is a hydrocarbyl selected from the same group as R, --R¹COOR² or --R³ OZ and X represents the residue obtained by removal of (a)the hydrogen from the sulfur atom of a mercaptide, a mercaptoalkanolester, a mercaptoacid ester or a thiocarboxylic acid, (b) the hydrogenfrom the carboxyl group of a carboxylic acid or (c) the hydrogen from ahydroxyl group of a mono- or polyhydric alcohol or phenol.
 3. Animproved composition according to claim 2 wherein R represents alkylcontaining from 1 to 20 carbon atoms.
 4. An improved compositionaccording to claim 2 wherein R¹ is methylene or ethylene and R² is alkyland contains from 1 to 20 carbon atoms.
 5. An improved compositionaccording to claim 2 wherein R³ is ethylene and Z is hydrogen, theresidue obtained by removing the hydrogen from the carboxyl group of amono-carboxylic acid containing from 1 to 20 carbon atoms, or theresidue obtained by removing the hydrogen from one carboxyl group of adicarboxylic acid containing from 2 to 20 carbon atoms or a half esterof said dicarboxylic acid.
 6. An improved composition according to claim2 wherein A is oxygen and R⁴ represents the hydrocarbyl portion of oleicacid.
 7. An improved composition according to claim 2 wherein R² is##STR17## and R¹ is methylene.
 8. An improved composition according toclaim 1 wherein said synergist exhibits a formula selected from thegroup consisting of ##STR18## wherein R¹², R¹³, R¹⁴ and R¹⁵ areindividually selected from the group consisting of hydrogen, halogen,amine, nitro, nitroso, sulfonyl, hydroxymethylene, alkyl containing from1 to 10 carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³and R¹⁴ or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstitutedphenyl group and R¹⁷ represents halogen, hydroxide or the residueobtained by removing the hydrogen atom from the carboxyl group of asaturated or ethylenically unsaturated carboxylic acid containing from 5to 22 carbon atoms.
 9. An improved composition according to claim 1 orclaim 2 wherein said synergist exhibits a formula selected from thegroup consisting of ##STR19## wherein R¹², R¹³, R¹⁴ and R¹⁵ areindividually selected from the group consisting of hydrogen, halogen,amine, nitro, nitroso, sulfonyl, hydroxymethylene, alkyl containing from1 to 10 carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³and R¹⁴ or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstitutedphenyl group; R¹⁷, R¹⁸ and R¹⁹ are individually selected from the groupconsisting of halogen, hydroxide, alkyl, aryl, alkaryl and aralkylwherein an alkyl group or the alkyl portion of any alkaryl or aralkylgroup contains from 1 to 20 carbon atoms, ##STR20## or R¹⁷ and R¹⁸collectively represent --O--.
 10. An improved composition according toclaim 1 wherein said synergist exhibits a formula selected from thegroup consisting of ##STR21## wherein R¹², R¹³, R¹⁴ and R¹⁵ areindividually selected from the group consisting of hydrogen, halogen,amine, nitro, nitroso, sulfonyl, hydroxymethylene, alkyl containing from1 to 10 carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³and R¹⁴ or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstitutedphenyl group.
 11. An improved composition according to claim 1 or claim2 wherein said synergist exhibits a formula selected from the groupconsisting of ##STR22## wherein R¹², R¹³, R¹⁴ and R¹⁵ are individuallyselected from the group consisting of hydrogen, halogen, amine, nitro,nitroso, sulfonyl, hydroxymethylene, alkyl containing from 1 to 10carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³ and R¹⁴or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstituted phenylgroup; R¹⁷ and R¹⁸ are individually selected from the group consistingof halogen, hydroxide, R²⁰, --SR¹⁶, alkoxyl, aryloxyl, ##STR23## whereinR²⁰ is alkyl, aryl, alkaryl or aralkyl wherein any alkyl group or thealkyl portion of any alkaryl or aralkyl group contains from 1 to 20carbon atoms.
 12. An improved composition according to claim 1 or claim2 wherein said synergist exhibits a formula selected from the groupconsisting of ##STR24## wherein R¹², R¹³, R¹⁴ and R¹⁵ are individuallyselected from the group consisting of hydrogen, halogen, amine, nitro,nitroso, sulfonyl, hydroxymethylene, alkyl containing from 1 to 10carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³ and R¹⁴or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstituted phenylgroup; R¹⁷ and R¹⁸ are individually selected from the group consistingof halogen, hydroxide, alkyl, aryl, alkaryl and aralkyl, wherein anyalkyl group or the alkyl portion of an alkaryl or aralkyl group containsfrom 1 to 10 carbon atoms, mono- and polyfunctional alkoxy, mono- andpoly-functional aryloxy, ##STR25## or R¹⁷ and R¹⁸ collectively represent--O--.
 13. An improved composition according to claim 1 or claim 2wherein said synergist exhibits a formula selected from the groupconsisting of ##STR26## wherein R¹², R¹³, R¹⁴ and R¹⁵ are individuallyselected from the group consisting of hydrogen, halogen, amine, nitro,nitroso, sulfonyl, hydroxymethylene, alkyl containing from 1 to 10carbon atoms and aryl or a pair consisting of R¹² and R¹³ or R¹³ and R¹⁴or R¹⁴ and R¹⁵ are joined to form a substituted or unsubstituted phenylgroup; R¹⁷, R¹⁸ and R¹⁹ are individually selected from the groupconsisting of halogen, hydroxide, --OSiR²⁰ R²¹ R²², R²⁰, R²¹, R²²wherein R²⁰, R²¹ and R²² are alkyl, aryl, alkaryl or aralkyl wherein anyalkyl group contains from 1 to 10 carbon atoms, ##STR27##
 14. Animproved composition according to claim 1 or claim 2 wherein saidsynergist exhibits a formula selected from the group consisting of##STR28## wherein R¹², R¹³, R¹⁴ and R¹⁵ are individually selected fromthe group consisting of hydrogen, halogen, amine, nitro, nitroso,sulfonyl, hydroxymethylene, alkyl containing from 1 to 10 carbon atomsand aryl or a pair consisting of R¹² and R¹³ or R¹³ and R¹⁴ or R¹⁴ andR¹⁵ joined to form a substituted or unsubstituted phenyl group; R¹⁷ andR¹⁸ are individually selected from the group consisting of halogen,hydroxyl, alkoxy, aryloxy, siloxy, --SR¹⁶, ##STR29## or R¹⁷ and R¹⁸collectively represent --O-- or --S--.
 15. An improved compositionaccording to claim 1 wherein said synergist is selected from the groupconsisting oftris(t-butyl-o-phenylene)bis(phosphite) orthophenylenebis(benzodioxastibole) bis(o-phenylene)orthosilicatebis(o-phenylene)orthosilicate (as a polymer) bis(o-phenylene)stannatetris(o-phenylene)bis(borate) 4-tert-butyl-o-phenylene pyroboratebis(o-phenylene)bis(phosphite)anhydride orthophenylene chloroborinate4-t-butyl-o-phenylene bromoborinate orthophenylene hydrogen borateorthophenylene n-butyl borate S-n-octyl-4-t-butyl-o-phenylene thioborate4-t-butyl-o-phenylenedibutylaminoborinate orthophenylene phenylboronate4-t-butyl-orthophenylene t-butylboronate ortho-hydroxy-phenylchloroborinate orthohydroxyphenyl phosphoric acid orthophenylenephosphoric acid 4-t-butyl-orthophenylene chlorophosphoric acidortho-hydroxy-phenyl chloroborinate (as a polymer)[tert-butyl-1,2-benzenediolato(2-)]tin (II)[3,4,5,6-tetrabromo-1,2-benzenediolato(2-)]tin (II)[4-nitro-1,2-benzenediolato(2-)]tin (II)[2-hydroxy-3-methoxyphenolato(1-)]tin (II) 2-hydroxy-benzodioxastibolenaphthalene-2,3-dioxyphosphorus monochloride trimethylsilyloxybis-o-phenylene-dioxyphosphorane 2-hydroxy-naphthodioxastibole2-[di-n-butylhydroxyethylamino]4-t-butylbenzodioxastibole2-hydroxy-benzodioxastibole/n-propanol/ammonia coordination compound2-hydroxy-benzodioxastibole/glycerol/diethylamine coordination compound2-hydroxy-4-t-butyl-benzodioxastibole/triethanol amine complex hydroxybis-t-butyl-o-phenylene dioxyphosphorane o-hydroxyphenyl-o-phenylenephosphate t-butyl-o-phenylene-dioxydibutylstannane o-phenylenedioxy bistri-n-dodecylstannane t-butyl-o-phenylene-dioxy butylchlorostannanenaphthalene 1-carbopropoxyethyl borate ethylenebis(4-methyl-o-phenylene) diborate o-phenylenedioxy phenylstibonate3-methylol-o-phenylene borate 4-t-butyl-o-phenylenedioxy phosphorustrichloride 4-caproyl-o-phenylene octylborate o-phenylenedioxydiphenylsilane o-phenylenedioxy diphenylsilane (as a polymer)3,4,3',4'-diphenylene-methane di-2-ethylhexyl diboratepyridine/phenyl-o-phenylene borate complex and 1,3,2-benzodioxazincol.16. An improved composition according to claim 1 which is liquid andshelf-stable at ambient temperatures.
 17. An improved compositionaccording to claim 1 wherein said antimony compound is selected from thegroup consisting ofantimony tris(isooctylmercaptoacetate) antimonytris(isooctylmercaptopropionate) antimony tris(n-dodecylmercaptide)antimony tris(2-hydroxyethylmercaptide) antimonytris(3-hydroxypropylmercaptide) antimony tris(methylmercaptoacetate)antimony tris(butylmercaptoacetate) antimonytris(octadecylmercaptoacetate) antimony tris(2-mercaptoethylcaprylate)antimony tris(3-mercaptopropylstearate) antimonytris(pentaerythrityl-monocaprylatemonomercaptoacetate) antimony trioleate antimony n-dodecylmercaptide bis(isooctylmercaptoacetate)bis(antimony) tris(glycoldimercaptoacetate) and mixtures thereof.
 18. Animproved composition according to claim 1 wherein said bismuth compoundis selected from the group consisting ofbismuth(isooctylmercaptoacetate)₃ bismuth (isooctylmercaptopropionate)₃ bismuth(n-dodecylmercaptide)₃ bismuth (2-hydroxyethylmercaptide)₃ bismuth(3-hydroxypropylmercaptide)₃ bismuth (methylmercaptoacetate)₃ bismuth(butylmercaptoacetate)₃ bismuth (octadecylmercaptoacetate)₃ bismuth(2-mercaptoethylcaprylate)₃ bismuth (3-mercaptopropylstearate)₃ bismuth(pentaerythrityl-monocaprylate-monomercaptoacetate)₃ bismuth tri oleatebismuth n-dodecylmercaptide bis(isooctylmercaptoacetate) bis(bismuth)tris(glycoldimercaptoacetate) and mixtures thereof.